Multi-modal wireless devices are increasingly prevalent in both business and personal applications. One illustrative class of multi-modal devices includes cellular communications (e.g., voice and text, etc.) and global positioning system (GPS) capabilities in an integrated portable form. Such devices depend on wireless signal services provided by an external system or network in order to operate. Furthermore, when a multi-modal device is in mobile operation, it is often necessary to transfer between geographically-fixed wireless service areas (e.g., cellular zones, Wi-Fi® hot spots, etc.) in order to maintain continuous service.
Thus, a multi-modal device must be capable of handling the transition between service zones in terms of any changes that occur in the corresponding wireless signals, or an interruption in service may result. One common zone-transfer issue is that of Doppler shift in the operating frequency used by the portable multi-modal device and the corresponding wireless service resources. Other phenomena, such as temperature drift and component aging, affect the performance of multi-modal devices.